In applications where high voltage semiconductor devices operating in high voltage conditions are controlled, high breakdown voltage transistors are typically used in corresponding control circuits. For example, in traditional gallium nitride (GaN) power management applications, transistors such as laterally diffused metal oxide semiconductor (LDMOS), bipolar or high voltage metal-oxide-semiconductor field-effect transistors (MOSFETs) can be utilized to control the GaN devices operating in high voltage conditions. Since these control transistors typically have poor figure of merit (FOM), compared to the FOM of the GaN devices, which can thereby, for example, limit the operating frequencies of the GaN devices, the overall circuit (e.g. power management) can be limited in performance by the large, high voltage control transistors which can be difficult to charge and discharge quickly (e.g. their FOM is too high) and therefore the benefit of using the GaN devices can be substantially reduced. In addition to power management applications, high voltage signals may be found in amplifiers such as audio amplifiers (especially Class-D audio amplifiers); filter banks; and drivers for resonant circuits; and any other application in which peak voltages may exceed the voltage handling capability of the control circuits being used to achieve the application.
This application applies to those circuits with high side (HS) and low side (LS) controls that either pull a common output node up to a high voltage or pull the output node down to a low voltage (often a reference voltage or ground). Such circuits require efficiency, low distortion, high speed, flexibility, reliability and low cost. The current application addresses these issues by addition of dead time control to the parent application.
In such applications where high voltage devices are controlled, it can be desirable to tightly control timing of the ON state of the high voltage devices, so as to, for example, reduce or eliminate overlap time of the high voltage devices in the ON state.